often shed by apparently healthy animals and are capable of causing severe disease
in humans (Strydom et al. 2019; Younis et al. 2019).
Vibrio cholera It causes cholera, which is a gastrointestinal infection of the
intestine. The major symptoms are watery diarrhea, vomiting, and leg cramps.
Rapid loss of body fluids leads to dehydration and shock in affected patients. Lack
of medical attention can lead to death within hours of infection. V. cholerae enters
the human body via contaminated drinking water or by eating contaminated seafood.
The contamination of food or water occurs when untreated sewage is released into
the supply water system, affecting the potable water or any food washed in that
water. There are many reports on outbreaks and epidemics of cholera across the
world and it is a major killer in areas with unhygienic conditions and improper
sanitation (Hsueh and Waters 2019; Rijal et al. 2019). Shigella causes infectious
disease Shigellosis. Patients with shigellosis have diarrhea, fever, and stomach
cramps from the inception of the infection. Shigellosis does not last more than a
week. Infected persons may remain asymptomatic, but can still act as carriers. The
spread of Shigella can be reduced by proper handwashing techniques and
maintaining proper hygiene (Carias et al. 2019; Williams and Berkley 2018).
Viruses are host-dependent and their transmission via water and other environmental routes is scientifically established. The viruses transmitted via water are shed
with feces and infect through the mouth (Lodder et al. 2010). Each virus has a
specific recipient cell in the host body, which helps in its replication and infection.
These viruses can spread from the intestinal cell to other parts of the body and can
cause serious complications other than diarrhea. To date, no major outbreak or
epidemic has been recorded for water-transmitted viruses, but they have the potential
of rapid spread and causing an epidemic. For example, adenoviruses, enteroviruses,
astroviruses, hepatitis A and E viruses, noroviruses, sapoviruses, and rotavirus (Gall
et al. 2015; Bonadonna and La Rosa 2019).
1.3.3 Protozoa
Numerous protozoan pathogens, like microsporidia, amoebae, ciliates, flagellates,
and apicomplexans, originating in human or animal feces are frequently found in
waterbodies worldwide. The major protozoa causing waterborne infections are
species of microsporidia, the amoeba, Entamoeba histolytica, Giardia duodenalis
(G. lamblia), Toxoplasma gondii, and Cryptosporidium species (Shanan et al. 2015).
Most of these protozoa, in contrast to microorganisms and viruses that multiply
rapidly, need a living host for its lifecycle and generally, the incubation period is
2–3 weeks long. Accurate diagnosis of these protozoans remains a concern. Higher
molecular techniques may be employed for their identification, which will enable the
scientists to conduct epidemiological research relating these organisms and to come
up with a strategy for their prevention and management (Omarova et al. 2018).
6
S. Rath
in humans (Strydom et al. 2019; Younis et al. 2019).
Vibrio cholera It causes cholera, which is a gastrointestinal infection of the
intestine. The major symptoms are watery diarrhea, vomiting, and leg cramps.
Rapid loss of body fluids leads to dehydration and shock in affected patients. Lack
of medical attention can lead to death within hours of infection. V. cholerae enters
the human body via contaminated drinking water or by eating contaminated seafood.
The contamination of food or water occurs when untreated sewage is released into
the supply water system, affecting the potable water or any food washed in that
water. There are many reports on outbreaks and epidemics of cholera across the
world and it is a major killer in areas with unhygienic conditions and improper
sanitation (Hsueh and Waters 2019; Rijal et al. 2019). Shigella causes infectious
disease Shigellosis. Patients with shigellosis have diarrhea, fever, and stomach
cramps from the inception of the infection. Shigellosis does not last more than a
week. Infected persons may remain asymptomatic, but can still act as carriers. The
spread of Shigella can be reduced by proper handwashing techniques and
maintaining proper hygiene (Carias et al. 2019; Williams and Berkley 2018).
Viruses are host-dependent and their transmission via water and other environmental routes is scientifically established. The viruses transmitted via water are shed
with feces and infect through the mouth (Lodder et al. 2010). Each virus has a
specific recipient cell in the host body, which helps in its replication and infection.
These viruses can spread from the intestinal cell to other parts of the body and can
cause serious complications other than diarrhea. To date, no major outbreak or
epidemic has been recorded for water-transmitted viruses, but they have the potential
of rapid spread and causing an epidemic. For example, adenoviruses, enteroviruses,
astroviruses, hepatitis A and E viruses, noroviruses, sapoviruses, and rotavirus (Gall
et al. 2015; Bonadonna and La Rosa 2019).
1.3.3 Protozoa
Numerous protozoan pathogens, like microsporidia, amoebae, ciliates, flagellates,
and apicomplexans, originating in human or animal feces are frequently found in
waterbodies worldwide. The major protozoa causing waterborne infections are
species of microsporidia, the amoeba, Entamoeba histolytica, Giardia duodenalis
(G. lamblia), Toxoplasma gondii, and Cryptosporidium species (Shanan et al. 2015).
Most of these protozoa, in contrast to microorganisms and viruses that multiply
rapidly, need a living host for its lifecycle and generally, the incubation period is
2–3 weeks long. Accurate diagnosis of these protozoans remains a concern. Higher
molecular techniques may be employed for their identification, which will enable the
scientists to conduct epidemiological research relating these organisms and to come
up with a strategy for their prevention and management (Omarova et al. 2018).
6
S. Rath